In general, a microscope includes two lens groups in series, that is, an objective lens group and an ocular lens group for observing a minute structure that cannot be observed through a naked eye.
A stereo microscope including two ocular lens parts for observing an object through stereoscopic image for two eyes has been developed and come into wide use. In stereo microscope, there are two types of Abbe type in which optical axis of objective lens group is parallel to observe an object, and Greenough type in which optical axis of objective lens group forms an specific mechanical angle to object an object.
However, a conventional stereo microscope has a disadvantage of not adjusting three dimensional effect of stereoscopic image according to a user.